The 2000 Surgeon General's Report on Oral Health identified the relationship between improvement in periodontal health and glycemic control as an area in need of intervention studies. To date there has been no adequately powered clinical trial to address this question. The Diabetes and Periodontics Trial (DPT) is a multi-center, randomized, controlled single-masked Phase III clinical trial designed to address this need. The study will test whether non-surgical periodontal therapy (scaling and root planing) is effective in reducing HbA1c of patients with type 2 diabetes and untreated chronic periodontitis compared to a control group receiving no treatment. The primary study outcome will be change in HbA1c values at 6 months. Delayed treatment will be offered to the control group after the 6- month visit. Secondary aims will evaluate whether improvement in clinical measures of chronic periodontitis is related to changes in systemic inflammatory markers, HbA1c, and measures of insulin resistance in these patients. The proposed DPT is a collaborative effort that involves four Clinical Centers from Schools of Medicine and Dentistry in Birmingham, AL; Philadelphia, PA; San Antonio, TX; and Minneapolis, MN; a Core HbA1c Laboratory, also in Minneapolis, MN; a Study Chair's office, a Coordinating Center, and a Core Metabolic Laboratory, all at Stony Brook University, Stony Brook, New York. An independent Data and Safety Monitoring Board (DSMB) will evaluate the data at least annually to assess the risks and benefits of periodontal treatment. Six hundred adults (150/center) meeting specific eligibility criteria will be enrolled over a 2.5 year period and examined at baseline, 3 and 6 months; a standardized common protocol and a detailed Manual of Procedures will be used at all centers. This application seeks support for the activities of the Coordinating Center (CC). The major CC responsibilities include: 1) serving as a collaborative partner and providing epidemiologic and biostatistical expertise to the organization, design, conduct and analysis of the trial; 2) collaborating in the development and distribution of forms, documents and protocols; 3) responsibility for data management, processing and analysis; 4) developing, implementing and monitoring the randomization process; 5) preparing periodic reports to monitor study activities, safety issues, outcomes and data quality for the DSMB and routine monitoring reports for the other study committees; 6) participating in the design, analysis and publication of the study results; 7) responsibility for quality assurance protocols; 8) coordinating and documenting DSMB meetings; and, 9) collaborating with the Study Chair to coordinate and document study meetings and communications among centers. Separate applications have been submitted by the Study Chair and the four Clinical Centers. Having periodontal (gum) disease may make it more difficult to control blood sugar levels for people with type 2 diabetes. This study will test whether non-surgical periodontal disease treatment leads to improved blood sugar control. Improving the way people manage their blood sugar is key to preventing diabetes complications and reducing health care costs.